Our studies involving neuron specific enolase (NSE) have for the most part centered on clinical applications. We have further documented and characterized the utilization of serum NSE levels and NSE immunocytochemistry as diagnostic and prognostic tools in various neuroendocrine neoplasms. Specifically, we have further evaluated the effectiveness of monitoring the clinical course of both oat cell lung cancer and pediatric neuroblastoma utilizing our serum NSE radioimmunoassay. At the basic level, studies are currently being initiated to develop a specific suicide inhibitor for NSE that would have the potential to be labeled with positron emitters and used in diagnostic brain imaging. Our efforts are also continuing concerning the cloning of the NSE gene, which will greatly facilitate our studies of the differentiation of neurons. It is likely we will obtain the cDNA probe during the next year and perform some in situ hybridization studies. Since NSE is a marker for neuronal differentiation, the elucidation of factors which control its synthesis should provide basic insights concerning the molecular mechanisms involved in neural maturation.